Auto Blueberry First Time Window

A bit more growth this week, a few more leaves sprouting up. The first leaves to grow have started to yellow slightly. Is this normal? I think maybe they die off as the rest grows? Keeping it on the 18hr to 6 hr light schedule. I am rotating it slightly, at 8am I leave the plant on the window ledge with the lights on. At 12pm then the lights go off and its straight sunlight until about 7pm when the lights go back on until 2am. I also have been using a dyson airblade to help keep the temperature up as some evenings have been really cold. I am still only watering 118ml per day. Should I increase this? Also what nutrients should I use? I have been thinking to use tomato feed as I heard this works well and is easily available in my country.